1. Field of the Invention
This invention relates to data processing systems. More particularly, this invention relates to data processing systems that have an instruction interpreter that replaces a slow form instruction with a fast form instruction and that operates using a separate instruction store and data store.
2. Description of the Prior Art
It is known to provide Harvard architecture systems in which a separate data store and instruction store are provided. The separate data store and instruction store may typically be in the form of a separate data cache and instruction cache. Whilst there are advantages associated with such an arrangement, one problem it produces is how to deal with instruction code that is dynamically altered at runtime. In particular, it is known to provide an instruction interpreter that will modify a slow form of instruction to a fast form of instruction at runtime. In a Harvard system, the instructions are typically provided within a read only store and the writing of a modified form of instruction out to the data store would entail a performance reducing flush and reload of at least some portions of the data and instruction stores or risk problems due to inconsistency between different forms of the same instruction being held in the instruction store and the data store.